Generally, a multichamber-type processing apparatus, which includes a transfer chamber provided with a transfer arm and coupled to a plurality of processing chambers via gate valves, is known as a processing apparatus for performing etching, ashing, and deposition processes on a plurality of substrates, such as semiconductor wafers or glass substrates, producing high throughput. (see Japanese Patent Laid-open Publication No. 1994-31471)
An electrostatic chuck is frequently used as a jig to electrostatically adsorb a substrate to be processed, such as a semiconductor wafer in a processing chamber. Such electrostatic chuck incorporates therein an electrode embedded in a dielectric member, and by applying a direct current to the electrode the substrate is electrostatically adsorbed to a surface of the dielectric member by an electrostatic force, such as a Johnsen-Rahbek force or a Coulomb force.
In case that the substrate is adsorbed to the electrostatic chuck, a small amount of electric charge still remains in the substrate even after the application of the direct current to the electrode is stopped after the substrate is processed. The electric charge remaining on a surface of the substrate in the multichamber-type processing apparatus becomes an issue when transferring a substrate from a processing chamber to another processing chamber by use of the transfer arm. That is, the substrate becomes misaligned on the transfer arm when the transfer arm mounts thereon the substrate from the electrostatic chuck. Hence, when the substrate is transferred from the transfer arm to a processing chamber, the substrate is placed at a misaligned position in the processing chamber. Additionally, such condition also suffers from that it takes a relatively longer amount of time to separate the substrate from the electrostatic chuck, which in turn deteriorates throughput efficiency of the multichamber-type processing apparatus.
In order to eliminate such ill effects thereof, the charge on the substrate needs to be neutralized. For instance, there are a method of applying a current having an opposite polarity to the current applied to an electrode when a substrate is electrostatically adsorbed to an electrostatic chuck as disclosed in Japanese Patent Laid-open Publication 1997-213780 and a method of neutralizing charge on an object to be processed which is electrostatically adsorbed to an electrostatic chuck, by supplying ionized processing gas thereto as disclosed in Japanese Patent Laid-open Publication No. 1994-275546.
However, there are drawbacks associated with the method disclosed in Japanese Patent Laid-open Publication No. 1997-213780. In such method, it is difficult to apply the current to the substrate so as to precisely neutralize the electric charge, and thus either positive or negative electric charge still remains on a surface of the substrate when a desired valance is not obtained, reducing neutralization of the substrate.
Furthermore, in case of employing the process disclosed in Japanese Patent Laid-open Publication No. 1994-275546 there is a concern for damages incurring on the substrate such as the semiconductor wafer, by the ionized processing gas supplied thereto.